JP4072507B2 - Oil / water separator - Google Patents

Description

  The present invention relates to an oil / water separator, and more particularly to an oil / water separator using a floating separation method using fine bubbles.

  In the conventional oil-water separator by the flotation separation method described in Patent Document 1 below, pressurized air is mixed and dissolved in the processing liquid pumped from a large-capacity processing tank by a gas-liquid mixing means, The excess air that could not be dissolved is removed in the pressurized tank, and then the treatment liquid is returned to the treatment tank. At that time, fine bubbles are generated by spraying and depressurizing from the pressure valve, and these fine bubbles adhere to the oil. The oil floats in the water and separates the oil and moisture.

JP-A-5-317847

  In the above prior art, air that could not be dissolved in the processing liquid by the outlet of the gas-liquid mixing means becomes a large bubble in the processing tank and lowers the floating separation performance. It is open.

  However, inside the pressurized tank, large bubbles cause oil particles to float and cause oil / water separation to generate floating oil on the gas-liquid surface, so that the floating oil exists on the gas-liquid surface inside the tank. This floating oil is mixed little by little in the processing liquid by the wave motion of the gas-liquid surface. Therefore, the treatment time for reducing the treatment liquid in the treatment tank to an oil concentration that can be directly drained is very long.

  Since the pressurized tank is under pressure, the bubble diameter of the surplus air becomes small and the ascending speed becomes slow. Therefore, the pressure tank becomes large to separate the surplus air, and the apparatus becomes large.

  Further, when the processing target is a compressor drain, a small amount of processing liquid is continuously discharged, and the flow rate and oil concentration change depending on the amount of moisture in the atmosphere. In addition, the installation area of the oil / water separator itself may be limited, and it is desirable to reduce the size of the treatment tank. And if the size is simply reduced, the circulating flow that goes up and down in the treatment tank becomes stronger, and the oil particles that have floated up to the liquid level once descend on the water and descend to the vicinity of the bottom of the treatment tank. It will not be below.

  Increasing the amount of processing liquid ejected from the pressure valve to generate a large amount of fine bubbles from the pressure valve in order to improve the oil separation performance makes the circulating flow up and down in the treatment tank stronger and lowers the oil-water separation performance. To do.

  Therefore, an object of the present invention is to provide an oil-water separation apparatus based on a flotation separation method that can process even a small treatment tank at a high speed up to a low oil concentration.

  In order to achieve the above object, in the present invention, air is mixed with the processing liquid sent to the processing tank, the processing liquid in which the air is dissolved is discharged into the processing liquid in the processing tank, and the air dissolved in the processing liquid is discharged into fine bubbles. In an oil-water separator that separates oil and water by floating the oil in the treatment liquid by supplying it to the treatment liquid in the treatment tank, a plurality of chambers are divided between the chambers in a pipe that sends the treatment liquid to the treatment tank The bubble crushing means connected in multiple stages through the openings was provided.

  According to the present invention, the treatment liquid creates a circulation flow in each chamber of the bubble crushing means, and the mixed air is divided and refined by the circulation flow. Since the chamber is multi-staged, miniaturization is promoted, and not only large bubbles are greatly reduced by the miniaturization, but also the surface area of gas-liquid contact is greatly increased and the amount of dissolved air in the processing liquid is increased.

  Therefore, the amount of fine bubbles to be supplied to the treatment tank can be filled with a small amount of liquid sent in the pipe, the liquid feed speed can be lowered, and the treatment liquid in which the air released into the treatment liquid in the treatment tank is dissolved The speed of the oil is reduced, the circulation flow of the treatment liquid in the treatment tank is reduced, and the oil component separated and floated on the liquid surface can be prevented from falling, and the separation performance is not lowered.

  Therefore, even if the treatment tank is small, oil / water separation can be performed at high speed and reliably even to a low oil concentration that can be discharged directly to the drainage channel.

  Hereinafter, embodiments shown in the drawings will be described.

  In FIG. 1 which shows the oil-water separator 10 which is one Embodiment of this invention, the inside of the processing tank 11 is divided into the isolation | separation part 81 and the floating oil receiving part 83 by the shielding board 12, and the isolation | separation part 81 is The processing liquid W is stored and oil-water separation is performed, and the floating oil receiving portion 83 receives the oil component separated and floated by the separating portion 81 and overflowing the shielding plate 12. The shielding plate 12 is disposed so as to be higher than the designed processing liquid surface position 61 and the floating oil surface position 62.

A large bubble separation unit 13 is provided outside the processing tank 11, and a nozzle 33 that discharges a processing liquid is disposed inside the large bubble separation unit 13, and communicates from the large bubble separation unit 13 to an upper portion and a lower portion of the separation unit 81. A large bubble discharge pipe 14 and a circular pipe line 16 are provided.

  The pipe line 16 is provided with a plurality of openings 17 for discharging the processing liquid to the separation unit 81, and the total area of the openings 17 is smaller than the cross-sectional area of the pipe line 16. When the cross-sectional area of the pipe line 16 is sequentially reduced in the pipe length direction to make the flow velocity in the pipe line constant, the distribution amount in each opening 17 becomes more uniform.

  The large bubble discharge pipe 14 having a lower end connected to the upper portion of the large bubble separator 13 is inserted into the separation unit 81 from the vicinity of the intermediate portion in the height direction of the treatment tank 11, and the upper end of the large bubble discharge pipe 14 is the upper surface of the treatment liquid. It opens in the vicinity. The large bubble separator 13 removes large bubbles that have been generated, but is not pressurized and the upper part is open and free, and the fine bubbles released from the pipe 16 to the separation unit 81 Does not affect the.

  The separation unit 81 is provided with a discharge pipe 41 for discharging a clean processing liquid from the upper part. The separation pipe 81 discharges from below the processing liquid level position 61 of the separation unit 81, and once lifts up to the processing liquid level position 61, downstream thereof. Is piped to a position lower than the processing liquid level position 61. A valve 42 is provided in the middle of the discharge pipe 41. In addition, the partition plate 15 prevents the fine bubbles and oil particles rising in the separation unit 81 from entering the processing liquid flowing into the discharge pipe 41 from the separation unit 81 around the pipe seat of the discharge pipe 41 in the separation unit 81. The suction part 82 is formed. In other words, the speed of the fine bubbles and oil particles rising in the separation unit 81 is made higher than the speed of the processing liquid flowing into and flowing into the suction unit 82 to prevent mixing.

  A pipe 30 constituting a processing liquid circulation system is connected to the bottom of the separation unit 81. The pipe 30 is connected to the second pump 31 via a valve 36, and the outlet side of the second pump 31 is connected to the pipe 37 and bubbles. A pulverizer (bubble pulverizing means) 38 and a pipe 39 are connected to the nozzle 33 provided in the large bubble separator 13. An air supply pipe 35 that introduces air is connected to the pipe 30 via a valve 34, and further, a supply pipe 23 that constitutes a processing liquid introduction system is connected to the first pipe 21. And a valve 22 is provided.

  An oil discharge pipe 51 for discharging oil is provided at the bottom of the floating oil receiving portion 83. Although not shown in the drawing, pipes are provided outside from the bottom of the separation unit 81, and a valve is provided in the middle thereof, and these are used when it is necessary to discharge the processing liquid inside the separation unit 81. The supply pipe 23 may be connected to the lower part of the separation unit 81 so that the processing liquid is directly supplied to the separation unit 81.

  FIG. 2 is a longitudinal sectional view showing the bubble pulverizer 38. The bubble pulverizer 38 communicates a plurality of rooms R1 to Rn in multiple stages through the openings P of the partition plate B between the rooms. The opening P of the partition plate B is provided in the center of the partition plate B as shown in FIG. The cross-sectional area Ap of the opening P of each partition plate B is equal to the cross-sectional area Ah of the pipes 37 and 39 that send the processing liquid to the processing tank 11, and the flow path of the processing liquid that communicates with the opening of each partition plate is bubble crushing It rises from an inlet E below the box of the vessel 38 toward an outlet D above.

Next, the operation will be described.
The apparatus 10 of FIG. 1 can operate in two ways: continuous operation and intermittent operation.
Initially, the continuous operation | movement which supplies a process liquid continuously is demonstrated.

  First, the second pump 31 is operated in a state where the separation unit 81 of the treatment tank 11 is filled with fresh water or a treated liquid. At this time, the valve 34 and the valve 36 are opened. As fresh water or treated liquid from the valve 36 flows through the pipe 30, the air supply pipe 35 side becomes negative pressure, and air flows from the air supply pipe 35. The inflowing air is mixed in the liquid flowing in the pipe 30 and dissolved in the process of being pressurized by the second pump 31.

  The undissolved air flows from the lower part of the bubble crusher 38 downstream of the second pump 31 to increase the amount of dissolution, and is discharged into the large bubble separator 13 from the nozzle 33 together with the dissolved liquid. The liquid and air to which pressure has been applied by discharging from the nozzle 33 is reduced in pressure, the air dissolved in water becomes fine bubbles, and the air that cannot be completely dissolved becomes large bubbles.

  By providing the bubble crusher 38, large bubbles are greatly reduced. The reason for this is that, as shown in FIG. 2, every time the air flows into the plurality of chambers R1 to Rn of the bubble crusher 38 from the opening P of the partition plate B, a circulating flow occurs in each of the chambers R1 to Rn, and the flowing liquid flow circulates. The bubbles are divided and refined by stirring in the flow. Each time it passes through each of the rooms R1 to Rn, the surface area is increased and the air is dissolved in the liquid.

  Since the cross-sectional area Ap of each opening P is equal to the cross-sectional area Ah of the pipes 37 and 39, almost no decompression occurs when flowing into each of the rooms R1 to Rn from each opening P, and dissolved air and fine bubbles are not generated. There is an advantage that a fine state and a dissolved state can be maintained without forming large bubbles.

  Moreover, since the bubble crusher 38 is arranged vertically and the liquid flows in from below, no air pool is generated in the ceiling of each of the rooms R1 to Rn, the amount of dissolved air increases, and the theoretical dissolution Approach the amount.

  As for the bubbles that could not be refined by any means, the large bubble separator 13 has a characteristic that the rising speed in the liquid increases as the bubble diameter increases, so that the large bubbles accumulate on the upper portion of the large bubble separator 13 and the large bubbles. It is discharged from the discharge pipe 14 to the upper part of the separation part 81.

  Accordingly, a liquid containing only fine bubbles flows out from the opening 17 of the pipe line 16 following the outlet of the large bubble separator 13 to the separation unit 81. The liquid flowing out from the opening 17 is mixed with the liquid present in the separation unit 81 and flows while decelerating.

  As shown in FIG. 4, the flow forms a circulation flow in the separation portion 81, and a strong circulation flow is formed around the pipe line 16 by the flow from the opening 17 and the downward flow toward the pipe 30. A weak circulating flow is formed along with the rising of fine bubbles.

  When the strong circulation flow at the lower part of the separation unit 81 is integrated with the circulation flow at the upper part of the separation unit 81, the fine bubbles cannot be separated from the circulation flow. For this reason, the pipe line 16 is protruded into the separation part 81 and the flow rate is evenly distributed in the length direction of the pipe line 16 to prevent the circulation flow from becoming strong locally. Thus, the generation of large bubbles is suppressed and the supply amount of fine bubbles is increased, the flow rate of the liquid flowing out from the opening 17 is reduced to weaken the circulating flow accompanying the outflow, and the descending speed of the liquid sucked into the pipe 30 Since the circulating flow is weakened by the decrease, the fine bubbles can float without being influenced by the descending circulating flow.

  While maintaining this operation state, the first pump 21 is driven to open the valve 22 to operate the processing liquid supply system, and the processing liquid containing oil is mixed with the fresh water or the processed liquid circulating in the processing liquid circulation system. . Then, oil particles flow out from the openings 17 together with the fine bubbles, and the fine bubbles adhere to and float on the oil, so that the oil can be separated.

  As described above, the amount of the treatment liquid flowing out from the opening 17 is small, and the circulating flow descending in the separation unit 81 is weakened, but the amount of fine bubbles is large, so that the oil is almost attached to the fine bubbles and floats. However, even if it rises, it does not descend in the circulating flow, so that the oil can be reliably separated even in the separation portion 81 having a small volume.

  Then, the treated liquid is sucked at a speed slower than the rising speed of the fine bubbles from the suction part 82 which is the upper part of the separation part 81 by opening the valve 42 and naturally flows out from the discharge pipe 41.

  The supply amount of fine bubbles is proportional to the flow rate of the liquid to be treated, but considering that the normal pressure of the circulating water is 0.3 to 0.8 MPa and the amount of dissolved air is proportional to the pressure, the circulating water flow rate is the processing liquid flow rate. 30 to 100 times. Therefore, since the processing liquid is diluted 30 to 100 times with circulating water, the processing liquid supplied to the separation unit 81 has a low concentration.

In this continuous operation , the oil in the processing liquid that has passed through the processing liquid circulation system is processed within the time during which the processing liquid ascends the separation unit 81.

  The floating oil at the top of the separation unit 81 temporarily closes the valve 42 provided in the middle of the discharge pipe 41 during continuous operation, and raises the treatment liquid level position 61 and the floating oil level position 62 inside the separation unit 81, When close to the height of the shielding plate, the floating liquid floats over the shielding plate 12 and floats by utilizing the fact that the processing liquid level position 61 undulates due to the large bubbles occasionally discharged from the large bubble discharge pipe 14. The separated oil 63 is recovered from the pipe 51 by being discharged to the oil receiver 83.

  In addition, since the processing liquid always flows in the bubble crusher 38 arranged vertically as described above and no air pool is generated, there is an advantage that the oil hardly adheres to the inner wall and the cleaning work is not required.

Next, a description will be given of intermittent operation in which a certain amount of processing liquid is supplied and discharged after processing.

  First, the second pump 31 is operated in a state where the separation unit 81 of the treatment tank 11 is filled with fresh water or a treated liquid. At this time, the valve 34 and the valve 36 are opened.

  As fresh water or treated liquid from the valve 36 flows through the pipe 30, the air supply pipe 35 side becomes negative pressure, and air flows from the air supply pipe 35. When this operation is performed, the temperature of the fresh water or the treated liquid in the separation unit 81 rises due to heat generated by the second pump 31, and the density decreases.

  Subsequently, the operation of the processing liquid circulation system is stopped, the valve 22 of the processing liquid supply system is opened, the first pump 21 is operated, and a predetermined amount of processing liquid is supplied. The processing liquid flows into the separation unit 81 from the pipe 30 and the pipe 37, the bubble crusher 38, the pipe 39, the nozzle 33, the pipe line 16, and the opening 17.

  Since the processing liquid has a lower temperature and a higher density than the processing liquid in the separation unit 81, the processing liquid accumulates at the bottom of the separation unit 81, and the processing liquid having a lower density passes through the suction pipe 82 and the discharge pipe 41 and the valve 42. Discharged. For example, the volume below the upper end of the partition plate 12 of the separation unit 81 is 40 L, the temperature of the treatment liquid W of the separation unit 81 is 320 K, the temperature of the treatment liquid supplied (introduced) from the treatment liquid supply system is 283 K, and the supply of the treatment liquid When the amount is 20 L / h, only the treated liquid can be discharged by 30 L or more.

  Next, the processing liquid circulation system is operated with the valves 22 and 42 closed. The flow state in the separation part 81 is the same as that in FIG.

  Since the valve 42 is closed and bubbles are present in the processing liquid, the processing liquid level position 61 becomes higher than the highest position of the discharge pipe 41. In this state, the floating oil accumulates above the processing liquid level position 61 inside the separation unit 81, but the shielding plate 12 is disposed higher than the floating oil level position 62. When this operation is repeated, the floating oil accumulates at the top, and the difference between the floating oil surface position 62 and the processing liquid surface position 61 increases. By continuing until the processing liquid level position 61 becomes the same height as the shielding plate 12, the floating oil overflows (overflows) the shielding plate 12 and flows out to the floating oil receiving portion 83.

  In a normal screw compressor, about 1 mm of floating oil is accumulated by continuous operation for one week, and is discharged about once a week. This discharge time can be determined not only by the operation time but also by measuring the floating oil amount and the floating oil thickness.

  Since the oil concentration of the processing liquid W in the separation unit 81 from which the floating oil is discharged is low, the processing liquid circulation system is operated to raise the temperature of the processing liquid W in the separation unit 81, and then the processing liquid is supplied from the processing liquid supply system. After supplying and discharging the treated liquid from the upper part of the separation unit 81 and filling the lower part with the untreated treatment liquid, the treatment liquid circulation system is operated again to perform oil-water separation.

In the intermittent operation in which the treatment liquid is intermittently supplied from this treatment liquid supply system, the clean water or the treated liquid and about 50% of the treatment liquid are mixed and processed in the separation unit 81. To a predetermined low concentration. The flotation separation method has a high processing capacity in the region where the oil concentration is high, and can process at high speed up to an intermediate concentration. The remaining small amount of oil, that is, the low-concentration processing liquid has a low processing capacity, but can be processed in a relatively short time because it is processed in the amount existing in the separation unit 81. However, since this method requires time for supplying the processing liquid and discharging the processed liquid, the processing amount per unit time of the entire processing is small, and this processing method is suitable for a high concentration liquid to be processed.

  FIG. 5 shows another embodiment of the bubble pulverizer 38. In the bubble pulverizer 38 shown in FIG. 5, the openings P in the partition plate B are provided alternately so that the flow path in the bubble pulverizer 38 meanders.

  With this configuration, the processing liquid does not pass through each of the rooms R1 to Rn, and always forms a circulatory flow to form a turbulent flow, divides bubbles and refines them.

  6 and 7 show the position and shape of the opening P provided in the partition plate B. FIG. In the form of FIG. 6, two circular openings P1 and P2 are provided, and in the form of FIG. 7, semicircular openings P1 to P4 are provided around the inner wall. Such partition plates B may be appropriately combined to complicate the flow path in the bubble crusher 38 and cause turbulence. In addition, when providing many opening in each partition plate B, if the sum total of the cross-sectional area of opening in each partition plate B is made equal to the cross-sectional area of piping 37 and 39, it will be in the process liquid which passes each opening. Depressurization does not occur and does not return to large bubbles.

  Next, selection of the two operation methods will be described.

  FIG. 8 shows the relationship between the drain flow rate and oil concentration of a general screw compressor. When the amount of moisture in the atmosphere corresponding to summer is high, the drain flow rate is high and the oil concentration is low. When the amount of moisture in the atmosphere corresponding to winter is small, the drain flow rate is small and the oil concentration is high.

  In order to process this whole range by one operation method, a large machine having the capability of the maximum oil flow concentration at the maximum drain flow rate is necessary, and there is a problem in terms of installation area and cost. In addition, there is a method to control the treatment liquid supply with high accuracy, but it is necessary to measure the drain flow rate or oil concentration with high accuracy, which is problematic in terms of cost and when supplying a small amount of high oil concentration drain. There is a problem with the reliability of the pump.

  Therefore, by taking advantage of the characteristics of the two operation methods, a continuous treatment is performed when the drain flow rate is high and the oil concentration is low, and intermittent operation is performed when the drain flow rate is low and the oil concentration is high. An oil / water separator capable of high-speed processing can be configured.

  Although FIG. 8 shows continuous operation and intermittent operation, it is also possible to widen the margin in the intermediate region by using two patterns of intermittent operation. Information on the drain flow rate or oil concentration is necessary for selecting these operation patterns. Since there is no method for measuring the oil concentration in a short time, information on the drain flow rate is used for selecting an operation pattern. The drain flow rate can be calculated from the amount of moisture in the atmosphere, compressor discharge air pressure, air cooler outlet temperature, and condensate collection efficiency. Therefore, there is a method for measuring atmospheric temperature and atmospheric humidity. On the other hand, there is usually a method in which a tank for temporarily storing the drain from the compressor is provided, and a liquid level gauge is attached therein, and the drain flow rate is calculated from the change in the liquid level. It is also possible to measure only the atmospheric temperature, calculate the maximum drain flow rate with an atmospheric humidity of 100%, and use this value for control. In practice, these methods are used alone or in combination for control.

  An arrangement configuration when the oil-water separator 10 is embodied will be described with reference to FIG. FIG. 9 is in the form of the left and right reversed from FIG. The treatment tank 11 is disposed above because the treated liquid and the floating oil are discharged by gravity. In order to effectively use the lower space of the processing tank 11, the first pump 21 and the second pump 31 are arranged under the processing tank 11, a floating oil tank 71 is installed under the side, and these are connected by piping. ing. These are all housed in a housing.

  According to such an arrangement, the installation area can be reduced.

1 is an overall system diagram of an oil / water separator according to an embodiment of the present invention. It is a schematic longitudinal cross-sectional view of the bubble crushing means in the oil-water separator shown in FIG. It is a top view of the partition plate in the bubble crushing means shown in FIG. It is a figure explaining the flow of the process liquid in the separation part of the processing tank in the oil-water separator shown in FIG. It is a schematic longitudinal cross-sectional view of the bubble grinding | pulverization means which becomes another form in the oil-water separator shown in FIG. It is a top view of the partition plate which becomes another form in the bubble crushing means shown in FIG. It is a top view of the partition plate which becomes further another form in the bubble crushing means shown in FIG. It is a figure which shows the operating method of the oil-water separator shown in FIG. 1, the relationship between a drain flow rate, and oil content concentration. It is a figure which shows the arrangement configuration of each part at the time of actualizing the oil-water separator shown in FIG.

Explanation of symbols

10 ... Oil-water separator
11 ... Processing tank
12 ... Shield plate
16 ... pipeline
17 ... Opening
21 ... First pump
31 ... Second pump
33 ... Nozzle
37, 39 ... Piping
38 ... Bubble crushing means (bubble crusher)
B ... Partition plate
P ... Opening
R1-Rn ... Room
41 ... discharge piping
81. Separation part
83. Floating oil receiving part

Claims (4)

Air is mixed with the processing liquid sent to the processing tank, the processing liquid dissolved in the air is discharged into the processing liquid in the processing tank, and the air dissolved in the processing liquid is supplied to the processing liquid in the processing tank as fine bubbles. In the oil-water separator that separates the oil and water by floating the oil in the treatment liquid,
The piping for sending the processing solution in the processing tank, have a bubble breaking means comprising communicating a plurality of chambers in multiple stages through the opening in the partition plate between each room, the cross-sectional area of the openings of the partition plates in said bubble breaking means is An oil / water separator characterized by having a cross-sectional area equal to that of a pipe for sending a treatment liquid to a treatment tank . Air is mixed with the processing liquid sent to the processing tank, the processing liquid dissolved in the air is discharged into the processing liquid in the processing tank, and the air dissolved in the processing liquid is supplied to the processing liquid in the processing tank as fine bubbles. In the oil-water separator that separates the oil and water by floating the oil in the treatment liquid,
The piping for sending the processing solution in the processing tank, have a bubble breaking means comprising communicating a plurality of chambers in multiple stages through the opening in the partition plate between the room and communicating with the opening of the partition plate of said bubble breaking means processing An oil-water separator according to claim 1, wherein the liquid flow path rises from the lower inlet of the bubble crushing means toward the upper outlet . In the oil / water separator according to claim 2 , the openings of the partition plates are in alternate positions for each room, and the flow path of the processing liquid communicating with the openings of the partition plates is meandering. Oil-water separator. The oil-water separator according to claim 1 , wherein the sum of the cross-sectional areas of the openings is equal to the sum of the cross-sectional areas of the pipes in the partition plate provided with a plurality of openings. Separation device.

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